package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.lang.Tuple;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {
    @Resource
    private IUserService userService;
    
    @Resource
    private IFollowService followService;
    
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog ->{
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result queryBlogLikes(Long id) {
        String key=BLOG_LIKED_KEY+id;

        // 1.查询top5（前五个）的点赞用户 zrange key 0 4
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if(top5==null||top5.isEmpty()){
            return Result.ok(Collections.emptyList());
        }

        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",",ids);

        // 不能只用in，要不然是按id大小排序，而不是redis中查出来的排序
        List<UserDTO> userDTOS = userService.query().
                in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());

        return Result.ok(userDTOS);
    }

    @Override
    public Result likeBlog(Long id) {
        Long userId = UserHolder.getUser().getId();

        String key= BLOG_LIKED_KEY+id;

        // 使用有序集合（Sorted Set）,可以获取点赞排行榜较高的，而不用set
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        // 如果没点赞
        if(score==null){
            boolean isSuccess = update().setSql("liked=liked+1").eq("id", id).update();
            // 保存用户到Redis的set集合
            if(isSuccess){
                stringRedisTemplate.opsForZSet().add(key,userId.toString(),System.currentTimeMillis());
            }
        }else{
            // 取消点赞
            boolean isSuccess = update().setSql("liked=liked-1").eq("id", id).update();
            if(isSuccess){
                stringRedisTemplate.opsForZSet().remove(key,userId.toString());
            }

        }
        
        return Result.ok();
    }

    @Override
    public Result saveBlog(Blog blog) {
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());

        boolean isSuccess = save(blog);
        if(!isSuccess){
            return Result.fail("新增笔记失败");
        }

        // 查询笔记作者的所有粉丝
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();
        
        for(Follow follow:follows){
            Long userId = follow.getUserId();
            // 推送给粉丝
            String key=FEED_KEY+userId;
            // 在有序集合中，每个元素都关联一个分数
            stringRedisTemplate.opsForZSet().add(key,blog.getId().toString(),System.currentTimeMillis());
        }
        
        return Result.ok(blog.getId());
    }

    // 我关注的那些人的博客
    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        Long userId = UserHolder.getUser().getId();
        
        String key=FEED_KEY+userId;

        // 查询收件箱
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);

        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        
        List<Long> ids=new ArrayList<>(typedTuples.size());
        
        // 记录最小值
        long minTime=0;
        // 记录有多少个最小值一样的,下次查询就跳过这么多元素
        int os=1;
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) {
            ids.add(Long.valueOf(tuple.getValue()));
            // longValue() 是 Double 类的一个实例方法，其作用是将 Double 类型的值转换为 long 类型
            long time=tuple.getScore().longValue();
            if(time==minTime){
                os++;
            }else{
                minTime=time;
                os=1;
            }
        }

        // 根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();

        for (Blog blog : blogs) {
            queryBlogUser(blog);
            isBlogLiked(blog);
        }

        ScrollResult r=new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);

        return Result.ok(r);
        
    }

    // 根据博客id，查博客
    @Override
    public Result queryBlogById(Long id) {
        Blog blog=getById(id);
        
        if(blog==null){
            return Result.fail("笔记不存在！");
        }
        
        queryBlogUser(blog);
        isBlogLiked(blog);
        
        return Result.ok(blog);
    }
    
    private void queryBlogUser(Blog blog){
        Long userId=blog.getUserId();
        User user=userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }
    
    // 查询博客是否被点过赞，可以实现点赞高亮通过isLiked属性
    private void isBlogLiked(Blog blog){
        UserDTO user = UserHolder.getUser();
        // 用户未登录，无需查询是否点赞
        if(user==null){
            return;
        }

        Long userId = user.getId();
        String key=BLOG_LIKED_KEY+blog.getId();
        // 判断当前登录用户是否已经点赞
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        
        blog.setIsLike(score!=null);
    }


}
